Ruby Lazy Enumerator Demo

lazy_demo.rb

def lazy_demo(n, group_size:n, groups:n)
  (1..Float::INFINITY)
    .lazy
    .map{|x| x * n }
    .select{|product| product.even? }
    .each_slice(group_size)
    .map{|group| group.map(&:to_s).join(",") }
    .first(groups)
end

irb> puts lazy_demo(1)
2

irb> puts lazy_demo(2)
2,4
6,8

irb> puts lazy_demo(2, group_size: 5)
2,4,6,8,10
12,14,16,18,20

irb> puts lazy_demo(3)
6,12,18
24,30,36
42,48,54

irb> puts lazy_demo(3, groups: 9)
6,12,18
24,30,36
42,48,54
60,66,72
78,84,90
96,102,108
114,120,126
132,138,144
150,156,162